The medicinally used part of licorice is the root and dried rhizome of the
low-growing shrub Glycyrrhiza glabra . Currently, most
licorice is produced in Greece, Turkey, and Asia.

Licorice has been used in ancient Greece, China, and Egypt, primarily for
gastritis (inflammation of the stomach) and ailments of the upper respiratory
tract. Ancient Egyptians prepared a licorice drink for ritual use to honor
spirits of the pharaohs. Its use became widespread in Europe and Asia for
numerous indications.

In addition to its medicinal uses, licorice has been used as a flavoring
agent, valued for sweetness (glycyrrhizin, a component of licorice, is 50
times sweeter than table sugar). The generic name "glycyrrhiza"
stems from ancient Greek, meaning "sweet root." It was originally
used as flavoring for licorice candies, although most licorice candy is now
flavored with anise oil. Licorice is still used in sub-therapeutic doses as a
sweetening agent in herbal medicines, lozenges, and tobacco products (doses
low enough that significant adverse effects are unlikely).

Licorice has a long history of medicinal use in Europe and Asia. At high
doses, there are potentially severe side effects, including hypertension (high
blood pressure), hypokalemia (low blood potassium levels) and fluid retention.
Most adverse effects have been attributed to the chemical component
glycyrrhiza (or glycyrrhizic acid). Licorice can be processed to remove the
glycyrrhiza, resulting in DGL (deglycyrrhizinated licorice), which does not
appear to share the metabolic disadvantages of licorice.

These uses have been tested in humans or animals. Safety
and effectiveness have not always been proven. Some of these conditions are
potentially serious, and should be evaluated by a qualified healthcare provider.

Uses based on scientific evidence

Grade*

Apthous ulcers / canker sores

Some research suggests that licorice extracts, DGL and the drug
carbenoxolone may provide benefits for treating cankers sores. However,
studies have been small, with flaws in their designs. The safety of DGL
makes it an attractive therapy if it does speed healing of these sores,
but it is not clear at this time whether there is truly any benefit.

C

Atopic dermatitis

Topical licorice extract gel has been shown to be effective in the
treatment of atopic dermatitis in preliminary human study. Further
research is needed to confirm these results.

C

Bleeding stomach ulcers caused by aspirin

Although there has been some study of DGL in this area, it is not clear
what effects DGL has on gastrointestinal bleeding.

C

Familial Mediterranean Fever (FMF)

Early study of a multi-ingredient preparation containing licorice,
called Immunoguard, suggests possible effects in managing FMF.
Well-designed study of licorice alone is necessary before a
recommendation can be made.

C

Herpes simplex virus

Laboratory studies have found that DGL may hinder the spread and
infection of herpes simplex virus. Studies in humans have been small,
but they suggest that topical application of carbenoxolone cream may
improve healing and prevent recurrence.

In theory, because of the known effects of licorice, there may be some
benefits of licorice for high potassium levels caused by a condition
called hypoaldosteronism. There is early evidence in humans in support
of this use. However, research is preliminary and a qualified health
care provider should supervise treatment.

C

Peptic ulcer disease

Licorice extracts, DGL and carbenoxolone have been studied for treating
peptic ulcers. DGL (but not carbenoxolone) may offer some benefits.
However, most studies are poorly designed and some results conflict.
Therefore, it is unclear whether there is any benefit from licorice for
this condition.

C

Reducing body fat mass

Preliminary data shows that licorice may reduce body fat mass. Further
research is needed to confirm these results.

C

Viral hepatitis

The licorice extracts DGL and carbenoxolone have been proposed as
possible therapies for viral hepatitis. Further research is needed
before a recommendation can be made.

C

Genital herpes

Available studies have not found any benefit from carbenoxolone cream
when applied topically to the skin to treat genital herpes infections.

D

*Key to grades
A: Strong scientific evidence for this use;
B: Good scientific evidence for this use;
C: Unclear scientific evidence for this use;
D: Fair scientific evidence against this use;
F: Strong scientific evidence against this use.

Grading rationale

Uses based on tradition or theory

The below uses are based on tradition or scientific theories. They often
have not been thoroughly tested in humans, and safety and effectiveness have
not always been proven. Some of these conditions are potentially serious, and
should be evaluated by a qualified healthcare provider.

The below doses are based on scientific research,
publications, traditional use, or expert opinion. Many herbs and supplements
have not been thoroughly tested, and safety and effectiveness may not be proven.
Brands may be made differently, with variable ingredients, even within the same
brand. The below doses may not apply to all products. You should read product
labels, and discuss doses with a qualified healthcare provider before starting
therapy.

Adults (18 years and older):

Carbenoxolone gel or cream: A 2 percent cream or gel has been applied five
times a day for seven to 14 days for herpes simplex virus skin lesions.

Commercial preparation : 3. 5 grams a day of a commercial
preparation of licorice has been studied for body fat mass reduction.

DGL extract tablets: Doses of 380 to 1,140 milligrams three times daily taken
by mouth 20 minutes before meals have been used.

Licorice fluid extract (10 percent to 20 percent glycyrrhizin): Doses of 2 to
4 milliliters per day have been taken by mouth.

Licorice powdered root (4 percent to 9 percent glycyrrhizin): Doses of 1 to 4
grams taken by mouth daily, divided into three or four doses, have been used.

Children (younger than 18 years):

There is not enough scientific evidence to recommend licorice for use in
children, and licorice is not recommended due to potential side effects.

The U.S. Food and Drug Administration does not strictly
regulate herbs and supplements. There is no guarantee of strength, purity or
safety of products, and effects may vary. You should always read product labels.
If you have a medical condition, or are taking other drugs, herbs, or
supplements, you should speak with a qualified healthcare provider before
starting a new therapy. Consult a healthcare provider immediately if you
experience side effects.

Allergies

People should avoid licorice if they have a known allergy to licorice, any
component of licorice or any member of the Fabaceae (Leguminosae) plant family
(pea family). There is a report of rash after applying a cosmetic product
containing licorice to the skin.

Side Effects and Warnings

Licorice contains a chemical called glycyrrhizic acid, which is responsible
for many of the reported side effects. DGL (deglycyrrhizinated licorice) has
had the glycyrrhizic acid removed, and therefore is considered safer for use.

Many of the adverse effects of licorice result from actions on hormone levels
in the body. By altering the activities of certain hormones, licorice may
cause electrolyte disturbances. Possible effects include sodium and fluid
retention, low potassium levels, and metabolic alkalosis.

Electrolyte abnormalities may also lead to irregular heartbeats, heart attack,
kidney damage, muscle weakness, or muscle breakdown. Licorice should be used
cautiously by people with congestive heart failure, coronary heart disease,
kidney or liver disease, fluid retention (edema), high blood pressure,
underlying electrolyte disturbances, hormonal abnormalities, or those taking
diuretics.

Hormonal imbalances have been reported with the use of licorice, such as
abnormally low testosterone levels in men or high prolactin levels and
estrogen levels in women. However, study results conflict. These adverse
effects may reduce fertility or cause menstrual abnormalities.

Reduced body fat mass has been observed with the use of licorice. Acute
pseudo-aldosteronism syndrome has been associated with licorice. Paralysis has
been reported in a patient taking licorice that contributed to low potassium
levels. Thyrotoxic periodic paralysis (TPP) has been associated with licorice.
Metabolic alkalosis and seizure has been reported from licorice in antacid.

Licorice has been reported to cause high blood pressure, including dangerously
high blood pressure with symptoms such as headache, nausea, vomiting, and
hypertensive encephalopathy with stroke-like effects (for example, one-sided
weakness).

High doses of licorice may cause temporary vision problems or loss. Ocular
side effects have been reported. Central retinal vein occlusion has been
associated with licorice. A case report exists of licorice-induced hypokalemia
associated with dropped head syndrome (DHS).

Pregnancy and Breastfeeding

Licorice cannot be recommended during pregnancy and breast-feeding due to
possible alterations of hormone levels and the possibility of premature labor.

Hormonal imbalances reported with the use of licorice include abnormally low
testosterone levels in men and high prolactin levels/estrogen levels in women.
However, study results conflict. 17-OHP and LH levels may also be affected.

Most herbs and supplements have not been thoroughly
tested for interactions with other herbs, supplements, drugs, or foods. The
interactions listed below are based on reports in scientific publications,
laboratory experiments, or traditional use. You should always read product
labels. If you have a medical condition, or are taking other drugs, herbs, or
supplements, you should speak with a qualified healthcare provider before
starting a new therapy.

Interactions with Drugs

In general, prescription drugs should be taken one hour before licorice or two
hours after licorice because licorice may increase the absorption of many
drugs. Increased absorption may increase the activities and side effects of
some drugs (for example, nitrofurantoin). Phosphate salts have been shown to
increase licorice absorption. Liver metabolism of certain drugs may be
affected by licorice but further study is needed before a conclusion can be
drawn.

Because the toxicity of digoxin (Lanoxin®) is increased when potassium levels
are low, people who take digoxin and are interested in using licorice should
discuss this with their health care provider. Increased monitoring may be
necessary. Other drugs that may increase the tendency for irregular heart
rhythms are also best avoided when using licorice.

Licorice may reduce the effects of blood pressure or diuretic
(urine-producing) drugs, including hydrochlorothiazide and spironolactone. Use
of licorice with the diuretics hydrochlorothiazide or furosemide (Lasix®) may
cause potassium levels to fall very low and lead to dangerous complications.
Other drugs that can also cause potassium levels to fall too low and are best
avoided when using licorice include insulin, sodium polystyrene (Kayexalate®),
and laxatives. Chewing tobacco may increase the toxicity of licorice gums by
causing electrolyte disturbances.

Licorice may increase the adverse effects associated with corticosteroids such
as prednisolone, and monoamine oxidase inhibitors such as Isocarboxazid (Marplan®),
phenelzine (Nardil®), or tranylcypromine (Parnate®). Agents acting on
serotonin may also interact with licorice.

Licorice may reduce the effects of birth control pills, hormone replacement
therapies, or testosterone therapy.

In theory, licorice may increase the risk of bleeding when used with
anticoagulants (blood thinners) or antiplatelet drugs. Examples include
warfarin (Coumadin®), heparin, clopidogrel (Plavix®), or aspirin.

Interactions with Herbs and Dietary Supplements

Herbs with potential laxative properties may add to the potassium lowering
effects of licorice.